Axonal microtubules of crayfish nerve cord, and the filamentous material associated with their surfaces, are being studied using electron microscopic and biochemical methods. In addition, axoplasmic proteins are being studied and characterized by disc gel electrophoresis. Tubulin from nerve cord is to be isolated and the in vitro conditions determined for its assembly into microtubules having 12 protofilaments. The axoplasmic fate of radioleucine injected into ganglia will be studied by using autoradiography, electrophoresis,and scintillation counting of consecutive slices of nerve cord. Work on the rickettsial agent, Coxiella burneti, will involve high-resolution electron microscopic studies of binary fission in the organism such that a detailed sequence of events can be determined. Also, host cells infected with C. burneti will be examined for possible alterations in their ability to bind concanavalin A as compared with uninfected host cells. The technique to be used is that of tagging bound concanavalin A with horseradish peroxidase, then using the benzidine reaction to give an electron dense product indicating the presence of peroxidase. Concanavalin A binding of the rickettsiae themselves will be evaluated, particularly in relation to the two antigenic types which are known to exist.